Highly‐fuel‐efficient Automobiles via Promoted NOx Decomposition (PND) by Electro‐Catalytic Honeycomb (ECH)
Ta-Jen Huang, Professor ([email protected]
Department of Chemical Engineering National Tsing Hua University Hsinchu, TAIWAN 1
How to achieve high fuel‐efficiency of automobiles Issues • Highest possible combustion temperature ↔ highest possible fuel efficiency [thermal efficiency]
→ Complete combustion of all precursors of combustible pollutants → Gasoline direct‐injection compression ignition (GDCI) engine fueled with light gasoline [light un‐branched open‐chain hydrocarbons (HCs)] ← no PM (particulate matter) *** Immediate solutions: Lean burn at best economy for gasoline engines Deleting EGR (exhaust gas recirculation) of diesel engines for highly‐increased fuel efficiency → Zero pollution of CO, HCs & PM. The remaining issue is high NOx control.
• Removal of high to low concentration NOx under oxygen‐rich condition → Removing very high NOx to near‐zero & completely oxidizing CO & HCs. • NOx emission control at engine cold‐start → No delay on NOx control. • No consumption of reducing agent on NOx control → No remain of the reducing agent, e.g. NH3, to cause secondary pollution. All these issues solved by Electro‐Catalytic Honeycomb (ECH).
The real‐world applicability of PND by ECH is confirmed by experimental data shown in the following.
How to increase the fuel efficiency of current gasoline automobiles? For gasoline cars, simply change the Air Fuel Ratio from 14.7 (stoichiometric burn) to 16.2 (lean burn for Best Economy*) [*as shown on the right].
This only needs to replace the Three‐way Catalytic (TWC) converter with the ECH. 3
How to increase the fuel efficiency of current diesel automobiles? For diesel cars, deleting EGR to highly increase the fuel efficiency and also to highly simplify the aftertreatment system (to one ECH only). This only needs to replace the Diesel oxidation catalyst (DOC) converter to the ECH and For new cars: deleting all other units (including all sensors) in the aftertreatment system. For old cars: simply close EGR and stop operating all other units (including all sensors’ electrical heating) in the aftertreatment system. 4
Gasoline direct‐injection compression ignition (GDCI) engine for very high fuel efficiency with zero pollution
EGR is not needed via ECH-deNOx GDCI can be for 2 & 4 cycle engine
• GDCI engine fueled with light gasoline [light un‐branched open‐ chain hydrocarbons ↔cetane] can have a fuel efficiency higher than current gasoline engine by 50% [a reduction of greenhouse gas emission by 50%] with zero pollution of CO & HCs without PM.
[S. Chu, A. Majumdar, Nature 488 (2012) 294; M.A. Ghadikolaei, Int. J.
Res. Eng. Tech. 3 (2014) 335]
• Light un‐branched open‐chain HCs [cetane]: alkane molecules with a cetane number of 100 ‐‐ can ignite very easily under compression.
• Fuels with higher cetane number have shorter ignition delays →more complete combustion↔less HCs & CO emission→zero pollution →higher combustion temperature↔higher expansion power →higher NO ←welcome by PND →less engine knocking↔more smooth and quiet engine 5 x
Current 2 cycle gasoline engine → GDCI can increase the fuel efficiency by 60% & be pollution free [intake fuel vapor → intake air]
Electro‐Catalytic Honeycomb (ECH)‐deNOx —
a real‐world device for Promoted NOx Decomposition (PND) • Lower emission of greenhouse gases (GHG) needs higher fuel efficiency, i.e., lower fuel (energy) consumption → cost down via PND.
• Currently, fuel efficiency is inhibited by difficulty in deNOx technologies (SCR reductant supply, NSR storage capacity limit…) to treat an exhaust with high NOx concentration. •
TWC can not treat lean‐burn exhaust.
• Higher combustion temperature leads to h